White scales/spots? Never seen this before.


What is the water volume of the tank? 70 gallons.
How long has the tank been running? Nearly two years.
Does it have a filter? Yes.
Does it have a heater? Yes.
What is the water temperature? 24⁰C.
What is the entire stocking of this tank? (Please list all fish and inverts.)
×1 Red rainbowfish.
×1 Blue rainbowfish.
×2 Boesemani rainbowfish.
×3 Yellow rainbowfish.
×1 Angelfish.
×3 Rainbow cichlids.
×1 Geophagus Steindachneri.
×1 Royal plec.

How often do you change the water? Once weekly.
How much of the water do you change? 50%.
What do you use to treat your water? Prime.
Do you vacuum the substrate or just the water? Just the water.

*Parameters - Very Important
Did you cycle your tank before adding fish? Yes.
What do you use to test the water? NTLabs liquid test kit.
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.
Ammonia: 0mg/L.
Nitrite: 0mg/L.
Nitrate: 20mg/L.
pH: 7.5.

How often do you feed your fish? Once or twice a day.
How much do you feed your fish? Enough to last a few minutes.
What brand of food do you feed your fish? Fluval Bug Bites, Hikari Massivore Delite, Vitalis Cichlid Pellets, King British Algae Wafers. Waiting for NLS Thera +A to arrive.
Do you feed frozen? Yes, Omega One frozen brine shrimp, daphnia and krill pacifica.
Do you feed freeze-dried foods? No.

Illness & Symptoms
How long have you had this fish? Three months.
How long ago did you first notice these symptoms? A few days ago.
In a few words, can you explain the symptoms? Some of the scales are now looking white.
Have you started any treatment for the illness? No.
Was your fish physically ill or injured upon purchase? Yes, with cysts. I got a bad batch of rainbows, and my LFS keeps getting in bad batches of them.
How has its behavior and appearance changed, if at all? No behavioural changes.

Explain your emergency situation in detail.
(Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)

So I got some rainbowfish for my 70 gallon three months ago, but when I bought them home, I discovered nasty white cysts on one of them. They've since healed up completely, however now I'm noticing some of the scales on this fish look as if they're turning white. I haven't seen anyhting like this before.

I can tell you it's not ich; spots are too big. I'm not confident the fish has lymphocystis anymore either, but it’s a possibility I guess.

The scales look as if they're turning white. Could it be hole-in-the-head?

This was a bad batch of rainbows. All of the rainbows at my LFS ever since have also come from a dubious vendor and show signs of ailments. I won't be buying from there for a while.

So I'm caring for them well, it's just that the fish probably came home with something.

Here are some images:

Any ideas what it could be?


Can't tell from pictures, but my first thought usually goes to ich or fungal. Doesn't look like ich but can't tell about fungal usually from a pic.


Yep, definitely not ich from the looks of things. It doesn’t look like fungus either though; it’s not fluffy and it’s spread out in small, neatly arranged specks.

HITH or lympho are the only things I can think of right now, but there’s uncertainty.

Those are the clearest photos I could get; fish darts whenever I take a photo. I’ll try again.


Anybody have any ideas what it could be?


Sorry A201, but I think I’ll tag you in this, as everyone seems to be just as unsure of what this is as I am.


I think the white scales are covering dead tissue, likely destroyed by Columnaris.
Not your fault, looks like you are providing an excellent environment for the fish.
Columnaris resides in most FW aquarium environments. It's an opportunistic bacteria, waiting to prey on a weakened fish.


Guessing I should euthanise before it spreads?

Could the red rainbow attacking the others in the morning contribute, or can rainbows put up with a bit of this behaviour?


Be a good idea to remove the infected fish asap and either euthanize or treat in a hospital tank.
It's been quite a while since I've kept Rainbows, but males will chase & bully, typical for larger boisterous shoaling fish.


I haven’t got a hospital tank, so euthanasia is my only option.

The chasing stops between 1pm and 2pm. I really gotta rehome the red rainbow, but he’s very healthy and vibrant (typical for the dominant fish) and the only place I can rehome him to, my LFS, is still getting in rough batches of rainbows and now has ich in the system thanks to this.

Columnaris likely infected this fish because he was particularly compromised from the start, with the prior cysts and all. The other rainbows are and have been healthier.

I’m beyond the point of being impatient with rainbowfish, so I’d like to slowly phase out of keeping them and replace them with a more peaceful, less expensive schooler. Where’s the fun in keeping fish that stress each other out to the point of becoming infected?


There are a lot of different species that are hyperactive morning swimmers, in particular Odessa Barbs & Filament Barbs. It's a form of mating behavior.
You might look at those particular Barb species as well as Denisoni Barbs. I've kept all of those varieties at one time or another. Very durable, colorful & active.


I just euthanised him. I could really observe the eaten-away tissue on the scales, making patterns. Euthanasia is never fun, but I feel a slight tad better after doing it.

Taking this morning’s discussion about denison barbs’ minimum footprint requirement into consideration, I wouldn’t want to risk these barbs because this tank’s footprint is 120cm x 40cm. I want to try something with a more laid-back temperament to that of rainbows and barbs, that’s still quite large (4-6 inches).

I’ll certainly look into other schoolers, thank you for your help. Rainbowfish are driving me absolutely crazy; wish I was never recommended that red one as a solitary centrepiece fish those years ago...

It’s a long, winding story as to how I ended up with rainbows, and such a weird combination of their species.



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I’m going to get Brazilian pennywort as a floater later on. The occasional nibble is ok, but eating it all up isn’t.

Those are really nice looking fish. I’ll look for those species or something similar when the time for that comes.

There’s not even half an hour before tomorrow, so I’m signing off for the night. Have a great rest of your day! :)


I have a question I was wondering for a while: does euthanising ill fish prevent the bacteria from spreading to other fish, or could healthy fish still fall ill if no treatment is made?


Columnaris infects weakened or injured fish. Healthy fish can usually fend off an infection.
An infected fish, allowed to remain in the display tank, can become a bacterial incubator. Upping the chances for tankmates to become infected.
It's a good idea to make a 50% WC after removing all obviously infected fish.



I’m leaning towards deep-bodied tetras as the replacement. I’ll probably end up rehoming the red rainbow and yellow rainbows, as they’re the joint problem (I’ve had this discussion earlier with others in person). The red rainbow attacks and chases the yellows every morning, leaving the yellow stressed.

After that I’m finished with rainbowfish. They’re hit or miss, but mostly miss.


Bleeding Hearts, Columbians, Diamonds, Buenos Aires & Congos are the thickest bodied Tetras I've kept.
If you want a big, thick & mean Tetra, in a species only tank, look at Exodons aka Buck tooth Tetra.
I've never kept them but have been tempted.


I've seen exodons. They're like little piranhas during feeding time!


They can literally peel the scales off tankmates. That's a big reason why I haven't tried them. Lol.


Not going to even bother trying exodons lol. I'm sure the King of DIY used to have some in his fish room.

I was browsing the world of deep-bodied tetras and many species are really appealing.

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